I have added your plugin to my site. Using the light skin.
On the admin user I could add one song and since then there is no more access possible to any profile.
It all ends in a superb error 500.
I can get back on the site after a cache cleaning on my browsers.
Uniactivating the Music Extreme plugin sorts it all out.
As this is a plugin one has to pay for I'd appreciate a solution, especially as it seems to be a great plugin.
I run Oxwall 1.7.2
Cheers,
Thomas